Whats good for increasing high RPM power?

CaifanSC

SCCoA Member
I hope nobody says turbo either :D ! (that comes laterz). Anyways the reason i ask is b/c i raced a friend of mine with a 90 SHO. It has cone filter, ported TB, MAF, and a few parts in the intake manifold, plug wires, chip, and exhaust. You can see what i have in my sig with the exception of a MAC intake, IC fan and very bad 3rd and 4th synchros :p . Anyways, we went from a stop and i got him good...saw his lights pretty far in my mirror....but around 90mph he was not only with me but passing me. By then i was about to (try) shift into 4th and he said he was still in second gear!! I've come to admire and love those DOHC's!

Anyways, my question is...what would increase upper rpm power? Now, ofcourse i know a free flowing exhaust will do marvels, but besides that whats good? Im tempted to think that the long lists of modifications available for our engines are focused in increasing that higher rpm powerband since down low we have no worries...but im not sure, hence i ask.
 
Just took a look at your member page...You don't have many mods to this point. High rpm power is something that you are not totally ready for at this point. I think what you are looking for is increasing your power band over the whole range. All I can say is to be prepared to spend some money. You can check my member page for my mods. I've got about $4400 invevsted in performance parts as of now, and I haven't tackled the high rpm power woes yet. I have actually taken my SC about as far as I can go for now without getting into the high rpm power makers. First and foremost is heads and cam. Those 2 things make a huge difference in power on the high end. Right now the exhaust ports aren't shaped properly for good high rpm power. Good porting, plus a matching cam can take care of that. Also the AR supercharger swap will increase your powerband up high as well. However, you will still be restricted by your head flow.

I'm not going to sit here though and tell you the best way to get this power is "XYZ" though. I'm simply making an observation and giving you my opinion on what you might want to consider doing. FWIW, I dyno'd 250 rwhp and 340 rwtq with my mods. My next step engine wise will be the heads/cam and AR for power. I have everything else in place to make the most of those mods. Take it for what it's worth. I'm just giving you an example of what I've done that has worked well for me.
 
Sam...that makes sence. I am nowhere near needing high rmp power...yet, but after my experience with the SHO i started wondering about it. All of us know that our cars are killer at low end b/c of the m90...but also b/c of the m90 power is reduced after a certain point in the curve.

I guess what i got from your message is that most of the mods we have available now sort of extend the power and efficiency of the m90...sort of prolonging our 'lower end' power and yet still have upper rpm possibilities? Like the AR...on that note, since its apparently in ur near future, how much are you looking to spend on the AR conversion?
 
Upper RPM power is not what the 3.8 was meant for it you notice at all the dyno charts most of them rarely exceed 5500RPM The SHO is s Yahmaha engine and can go to about 9K with cam mods and some short block fortification.

The 3.8 is a grunter as said before you need to make a broad power range. To make more power up higher you need to shift the torque band higher (cam timing), but the stock roller lifters pushrods, valves, retainers and springs are heavy and aren't meant for high RPM use. Besides the higher you ring it the faster it wears out.

Jeff
 
CaifanSC said:
Sam...that makes sence. I am nowhere near needing high rmp power...yet, but after my experience with the SHO i started wondering about it. All of us know that our cars are killer at low end b/c of the m90...but also b/c of the m90 power is reduced after a certain point in the curve.

I guess what i got from your message is that most of the mods we have available now sort of extend the power and efficiency of the m90...sort of prolonging our 'lower end' power and yet still have upper rpm possibilities? Like the AR...on that note, since its apparently in ur near future, how much are you looking to spend on the AR conversion?

I'm no where near the AR yet. I just dropped about $1k to get my car to the point of a tune, so the wife would be pretty upset if I went the next step and got the AR! I need to back off the car modding for a while. ;)

You did gather the right information from my post. You want to start with some other mods to increase your overall power. Once you get to a certain level, (heads, cam, performance rebuild...) you'd be able to pull 7-8k without too much of an issue. But most SC's make power to 6k after heads/cam. If you want a starting point, take a look at my mods. It's not the fastest way or the cheapest way to get to power, but it is solid. It's an example of something that has worked for me. Others have other things that have worked as well. I'd recommend that you find out where you want your car to be. Once you have that in mind, make a plan on how to get there. My end plan includes the AR and heads/cam. At this point, I have only to install larger injectors and I'm ready for those mods. I started out without a plan and ended up with a couple parts that I probably would not have gotten once my plan went into action. Be patient as well. Don't think that you have to go fast now. I've been working on my SC for 3 years now. (Well, my '89 for a couple, then everything got moved to my '92 in the last year.) And I'm finally at a point where I can just drive and enjoy my SC for a while. Make a plan and a good route to get to where you want to be. If you want, I can list how I've made my mods (in order) to show the progression of my mods.
 
There is no way you are getting 7-8K out of an SC engine, just look at the highest HP list. You will float the valves or spend big money on Ti valvetrain parts and a solid lifter cam, some light weight pistons and solid rods.

Jeff
 
I see the problem here, its fairly simple, yank the hood cable on the SHO from the fender liner and connect the lines from the IRC solenoid or whatever(dual runner intake) straight to vacuum? or is it absence of vaccum :confused: , whatever, not my problem, whatever keeps the butterflies for the shorter runners closed, this should limit his high RPM capability and give your slower car a much needed break against his well engineered powerplant :) . ITS ALWAYS ME ME ME ME ISNT IT, you have to think of the other guys :rolleyes:
 
J57ltr said:
There is no way you are getting 7-8K out of an SC engine, just look at the highest HP list. You will float the valves or spend big money on Ti valvetrain parts and a solid lifter cam, some light weight pistons and solid rods.

Jeff

If built right it will handle that rpm....Problem is that no one really builds it to handle that... There's a notion out there that these engines don't make any power above 5500 so there's not much done beyond that. It's true for the M90, but not so for the AR. It's only time until someone makes an engine that can handle 8k.
 
I think no matter what you do really, you wont take a SHO in the top-end. Before I go any further, I'm calling BS on your buddy! SHO's 2nd gear tops out at 67MPH at 7500RPM (I had a SHO MTX with a 3.2L swap), third gear will top out around 107-110ish at 7500RPM.
SHO's pull VERY well in the top-end due to those snakes. I think no matter what you do, you'll have trouble taking a SHO in the topend. When I had my SHO, I had the thing up to 120 and still pulling hard. My SC, the fastest I've had it up to was 110 (with mods in my sig) and after about 90mph or so, I could tell the SC didn't have anywhere near the pull the SHO did.
That's why those SHO bastards always want a roll race. Just fight em as much as you can into a deadstop.
 
To get more RPMs,you need more air.
Open up the IC & intake system after the blower.

I have no problem in pegging the tach
with a stock motor with bolt-ons.

You just need to make the parts.

Randy
 
007_SuperCoupe said:
If built right it will handle that rpm....Problem is that no one really builds it to handle that... There's a notion out there that these engines don't make any power above 5500 so there's not much done beyond that. It's true for the M90, but not so for the AR. It's only time until someone makes an engine that can handle 8k.

You can do anything with enough money, but the fact remains that the engine isn't made to handle that kind of stress. If you want to rev it that high it's going to take a LOT of money the type of forced induction is moot. Like I said before you will need strong rods light weight pistons and a valve train that is second to none. It's not a notion it's physics plain and simple.
Let's just make a set of DOHC heads for a obsolete design that is not very popular, that makes sense. :rolleyes:

To make a 3.8 that makes power to 8K on a regular basis,you will spend about 200 times what the car could ever be worth. 6.5K is about the limit I would ever go on this engine it just doesn't make any sense to go to 8K. With a cam to support level you would end up with a 2K idle.

Jeff
 
Randy N Connie said:
To get more RPMs,you need more air.
Open up the IC & intake system after the blower.

I have no problem in pegging the tach
with a stock motor with bolt-ons.

You just need to make the parts.

Randy


Hey Randy, i was under the impression that you COULD peg the tach (whenever it gets there) but after a certain RPM it just doesnt make more power enven if it revs out more.
 
Its a fact, one of the biggest reasons that the SC 3.8 bird motor
makes power down in the lower RPM Range,Or any motor is.

Short or no runner manifolds will make power in the lower RPM range.

If you want power to be made higher up the RPM range ,on any motor
be it carbuator,supercharge,turbo,3.8 SC you want a manifold with long or longer runners.

Thanks
 
you are all overlooking one very important thing.. Gearing!

A 94-95 5 speed with the factory 2.73 gears is pretty damn tall.

My first mod back in '99 was a set of 3.27:1 gears to my '92 5 speed.

With only the gear swap, k&n panel air filter, and removed silencer, I was consistantly about 2 carlengths ahead of a friends SHO from a 0-100 mph run.

The SHO has a lot shorter gearing, but doesn't have the torque of the SC off the line.. Basically the SHO has to play catch-up, and if your SC has stock rear end gears and no serious mods, the SHO will catch up. But for the stoplight to stoplight races (which are 90% of my encounters anyway), the SC owns the SHO..
 
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Mike yes I did go backwards.I think I will go eat another pain pill. :)

But are manifold, intake system is one reason that we have the low power band to RPM.

Thanks Randy
 
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LOL!!!!! I was pretty sure you just got mixed up on that. :)
I agree with you the stock SC's intake is so restrictive its kinda irelavent if it has any port runners or not. :( if not for the blower this motor is a slug.
What could be learned from this and how should we apply that knowledge?
 
Mike
They are many things wrong with the intake & the system in front of it.
The biggest reason why we stop making power above the 5000 RPM
range .Is the motor runs out of air.The air entances are to small for
enough air to even enter the manifold.Its not a hugh problem to worry
about flowting the valves,because there is not enough air entering the
stock set up to spin the motor fast enough.

I think it would take a book to write about are manifold flaws,If you want
to nit pick and go over ever little tid-bit.There are just so many reason.
why Ford did this & and that.And the physics of the end results.
There would be chapters for topics of the engieers,top dogs,bean counters
flow charts,physics,hood heigth,it would just go on and on.Why it is.

I can set down and talk and make since.But I am a pisspour comunicator
on line.

Are manifold is a plenum with six holes in the side of it.With no runners
I don't think a triangle in the center could be called a runner,air vain yes.
It is impossible to get much if any straight air flow to the ports.I think
if a person spent some time on developing air-vains would be of help.
But this is not easy with the room avalible in are designed manifold.
I have thought of adding a wall down the center of the manifold.With
directional vains leading to the ports.But this will create other problems
to be worked around.But this may be one way to raise the rpm power band.

Air flow is just like a car on the hole.You fix one problem.
then five more problems pop up that need to be delt with.

No one is going to take or spend much time to fix some problems with the SC.
Sc people either do not understand the the time & expense it takes to
make a pre-designed part better.Or even a new part,They flat don't care,or are to cheap,,,These people are there own worst enemies.when it comes to ever getting any parts.I have been doing parts most of my life.This group of bird people are constantly cutting there own throats when it comes to aftermarket parts.I have never
seen anything like it.A chevy bunch of Chevy guys could not do a better job.
to kill a parts market for thuunderbirds.

The post on this board are funny all the time.You read one post of whinning
about power.The next post consist of bashing.The next post talks about
some nice part someone is spending time and money on for others.The next post has pictures of cheap unfinished look alike junk parts stolen parts from the last post.

I am sure Iv made somebone mad again posting the truth.All I can say is
That when I die.I am going to be buried face down,So you can still kiss
my ***. :)

THANKS RANDY
 
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Jason Wild said:
has any one made there own lower intake I was looking at making one in my free time.

I have one,I think Mike has.And some SC 3.8 stang people have.I doubt that many will ever see them though.

Jason I got my brake lines finish.

Thanks Randy
 
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